We look at the division of 509370 by 12 
We're looking to find how many times 12 goes into 509370.

On to step 1:
If we divide 5 by 12, we get 0 and a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 5 leaves us with 5.
Take the next digit (0) from the dividend and append it to 5, then repeat: 50 / 12

Moving on to step 2:
12 goes into 50 4 times with a remainder of 2.
Write down 4 as next digit of the result. 
Result so far: 4.0
Deduct 48 from 50 and we're left with 2.
Take the next digit (9) from the dividend and append it to 2, then repeat: 29 / 12

Moving on to step 3:
When dividing 29 by 12, we get 2 with a remainder of 5.
The number 2 becomes the next digit in our result. 
Result so far: 42.0
If we take 24 away from 29, we end up with 5.
Take the next digit (3) from the dividend and append it to 5, then repeat: 53 / 12

Moving on to step 4:
If we divide 53 by 12, we get 4 and a remainder of 5.
The number 4 becomes the next digit in our result. 
Result so far: 424.0
Subtracting 48 from 53 leaves us with 5.
Include the next digit (7) from the dividend after 5, then repeat: 57 / 12

Step 5:
12 can be fit into 57 4 times, resulting in a remainder of 9.
Use 4 as the next digit of our solution. 
Result so far: 4244.0
Deduct 48 from 57 and we're left with 9.
Fetch the next digit (0) from the dividend, attach it to 9 and continue: 90 / 12

Going ahead to step 6:
The number 12 fits into 90 7 times, leaving a remainder of 6.
The next digit of our result is 7. 
Result so far: 42447.0
Subtracting 84 from 90 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 7:
12 goes into 60 5 times with a remainder of 0.
Write down 5 as next digit of the result. 
Result so far: 42447.5
Subtract 60 from 60 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 8:
12 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 42447.5
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 9:
12 goes into 0 0 times with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 42447.5
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

In conclusion, the division gives 42447.5 with a balance of 0.0.